Solve for $x$ and $y$ using substitution. ${6x+3y = -6}$ ${x = y-7}$
Answer: Since $x$ has already been solved for, substitute $y-7$ for $x$ in the first equation. ${6}{(y-7)}{+ 3y = -6}$ Simplify and solve for $y$ $6y-42 + 3y = -6$ $9y-42 = -6$ $9y-42{+42} = -6{+42}$ $9y = 36$ $\dfrac{9y}{{9}} = \dfrac{36}{{9}}$ ${y = 4}$ Now that you know ${y = 4}$ , plug it back into $\thinspace {x = y-7}\thinspace$ to find $x$ ${x = }{(4)}{ - 7}$ ${x = -3}$ You can also plug ${y = 4}$ into $\thinspace {6x+3y = -6}\thinspace$ and get the same answer for $x$ : ${6x + 3}{(4)}{= -6}$ ${x = -3}$